Height is the big one
On flat ground, a deck sits on a low frame with short posts. On a slope it needs taller posts, deeper beams, bracing and guarding on the high side, often steps too. In Middlesbrough, where so many gardens fall away from the house, height is usually the single biggest factor in the price.
Boards and frame
Treated softwood boards are the cheapest. Capped composite costs more per square metre but needs no staining and lasts much longer. Hardwood sits at the top end, partly because of the material and partly because it takes longer to fit. Composite also needs closer joists, which adds a little to the frame.
The extras that aren't really extras
Steps, balustrades, fascia boards and lighting are what make a deck safe and finished. They add to the cost, and on a raised deck they're essential rather than optional. We list them separately in our quote so you can see each one.
Ground and access
Heavy clay may need deeper post pads. Rubble, old patios or tree roots take time to deal with. If there's no side access and everything has to come through the house, that takes longer too. We look at all of this at the visit.
Comparing quotes fairly
When you compare prices, check that each one includes the same boards, the same frame spacing, guarding where it's needed, removal of any old deck and clearing up. A cheap quote that leaves out the frame detail or the steps isn't a cheaper deck.
Your questions
Why don't you publish prices?
Because they'd be misleading. Height, ground and access change the cost so much that any figure we put online would be wrong for most gardens. A visit and a quote are free.
Is a bigger deck cheaper per square metre?
Often slightly, because some costs such as the visit, setting out and steps don't grow with size. But a bigger deck is still more money overall.